Flexible spinal stabilization system and method

ABSTRACT

Devices, methods and systems for stabilizing at least a portion of the spinal column are provided. Devices include anchors and coupling members for engaging an elongate member. Systems include an elongate member sized to span a distance between at least two vertebral bodies and being at least partially formed of a flexible material. A number of anchors and coupling members are used to secure the elongate member to each of the vertebral bodies. The anchors can be compressed towards one another and the elongate member secured thereto and/or the elongate member can be tensioned to provide corrective forces to the spine.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.10/013,053 filed on Oct. 30, 2001, which is hereby incoporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to the field of instrumentation,devices, and systems for treatment of the spine, and more particularlyto methods and systems for interconnecting two or more portions of thespine and also devices for engaging an elongate member.

BACKGROUND OF THE INVENTION

The spine is subject to various pathologies that compromise its loadbearing and support capabilities. Such pathologies of the spine include,for example, degenerative diseases, the effects of tumors and, ofcourse, fractures and dislocations attributable to physical trauma. Inthe treatment of diseases, malformations or injuries affecting spinalmotion segments (which include two or more adjacent vertebrae and thedisc tissue or disc space therebetween), and especially those affectingdisc tissue, it has long been known to remove some or all of adegenerated, ruptured or otherwise failing disc. It is also known thatartificial discs, fusion implants, or other interbody devices can beplaced into the disc space after disc material removal. Externalstabilization of spinal segments alone or in combination with interbodydevices also provides advantages. Elongated rigid plates, rods and otherexternal stabilization devices have been helpful in the stabilizationand fixation of a spinal motion segment.

While the external stabilization systems of the prior art are a step inthe right direction, there remains room for additional improvements.Oftentimes, the geometric and dimensional features of these systems andpatient anatomy constrain the surgeon during surgery and prevent optimalplacement, attachment and loading of the spinal motion segment.

Thus, there is a general need in the industry to provide methods anddevices for stabilizing a spinal motion segment that reduce surgeonconstraints during surgery and optimize placement and attachment of thestabilization devices to the spinal motion segment. There are alsoneeded improved devices for connecting longitudinal members to thespinal column. There is also a need for stabilization devices that allowsegmental motion to be maintained after attachment thereto. There arefurther needs for stabilization devices that maintain the desiredcorrective forces on the spinal motion segment. The present invention isdirected to meeting these needs and others in a novel and unobviousmanner.

SUMMARY OF THE INVENTION

The present invention provides a system with anchors interconnected by aflexible elongate member. Coupling members secure the elongate member tothe anchors to maintain the corrective forces applied to the spinalmotion segment by the elongate member.

The present invention further provides an anchor to which an elongatemember can be attached. A coupling member can be coupled to the anchorto further secure the elongate member to the anchor.

The present invention also provides a cannulated anchor which receives aportion of a coupling member in the cannulation when the coupling memberis coupled to the anchor. An elongate member can also be placed betweenthe coupling member and the anchor, with the portion of the couplingmember extending through the elongate member.

The present invention also provides an anchor having a penetratingelement which at least partially penetrates an elongate member. Acoupling member can be secured to the anchor. In one form, thepenetrating element is received in the coupling member.

The present invention additionally provides a coupling member attachableto an anchor. The coupling member can be provided with any one of anumber of variously configured elongate member engaging portions thatpenetrate and/or crimp an elongate member positioned between thecoupling member and the anchor.

Methods for engaging an elongate member to a spinal motion segment arealso provided. According to one method, first and second anchors areengaged to first and second vertebrae and compressed toward one another.An elongate member is engaged to the first and second anchors. Accordingto another method, the elongate member is tensioned before it isattached to the anchors.

Further aspects, forms, objects, features, advantages and benefits ofthe present invention will become apparent from the drawings anddescription contained herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a spinal motion segment with a spinalfixation system according to the present invention attached thereto.

FIG. 2 is an elevational view of an anchor according to one aspect ofthe present invention.

FIG. 3 is a cross-sectional view through line 3-3 of FIG. 2.

FIG. 4 is a perspective view of a coupling member according to anotheraspect of the present invention.

FIG. 5 is an elevational view of the coupling member of FIG. 4.

FIG. 6 is a cross-sectional view through line 6-6 of FIG. 5.

FIG. 7 is an end view of the coupling member of FIG. 4.

FIG. 8 is an elevational view of an elongate member positioned in theanchor of FIG. 2 with the coupling member of FIG. 4 positioned forengagement to the anchor.

FIG. 9 is an elevational view of an elongated member positioned in theanchor of FIG. 2 with the coupling member of FIG. 4 engaged to theanchor and extending through the elongate member.

FIG. 10 is a perspective view of another embodiment anchor according tothe present invention.

FIG. 11 is a perspective view of another embodiment coupling memberaccording to the present invention.

FIG. 12 is an elevational view of the coupling member of FIG. 11.

FIG. 13 is a cross-sectional view through line 13-13 of FIG. 12.

FIG. 14 is a perspective view of another embodiment coupling memberaccording to the present invention.

FIG. 15 is an elevational view of the coupling member of FIG. 14.

FIG. 16 is a perspective view of another embodiment coupling memberaccording to the present invention.

FIG. 17 is an elevational view of the coupling member of FIG. 16.

FIG. 18 is a perspective view of another embodiment coupling memberaccording to the present invention.

FIG. 19 is a perspective view of another embodiment coupling memberaccording to the present invention.

FIG. 20 is a perspective view of another embodiment coupling memberaccording to the present invention.

FIG. 21 is another perspective view of the coupling member of FIG. 20.

FIG. 22 is an elevational view of another embodiment coupling memberaccording to the present invention.

FIG. 23 is an elevational view of another embodiment coupling memberaccording to the present invention.

FIG. 23 a in an end elevational view of the coupling member of FIG. 23.

FIG. 24 is an elevational view of another embodiment coupling memberaccording to the present invention.

FIG. 25 is a perspective view of the coupling member of FIG. 24.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is hereby intended, such alterations and further modificationsin the illustrated devices, and such further applications of theprinciples of the invention as illustrated herein being contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

FIG. 1 depicts a spinal stabilization system 20 according to oneembodiment of the present invention for stabilizing at least a portionof the vertebral column. Stabilization system 20 is shown attached to aspinal motion segment that extends across a plurality of vertebrae V1,V2, V3, V4, V5. Stabilization system 20 includes an elongate member 80secured to a plurality of anchors 30. Each anchor 30 is engaged to arespective one of the vertebrae V1, V2, V3, V4, V5. A coupling member 50is engaged to each of the anchors 30 with elongate member 80 positionedbetween each anchor 30 and its respective coupling member 50.

It should be understood that system 20 may be utilized in all regions ofthe spine, including the cervical, thoracic, lumbar, lumbo- sacral andsacral regions of the spine. It should also be understood that system 20may extend across a spinal motion segment having only two vertebrae ormore than two vertebrae. It is further contemplated two or morestabilization systems may be employed simultaneously along the samespinal motion segment. Additionally, although system 20 is shown in FIG.1 as having application in a posterior region of the spinal motionsegment, system 20 may alternatively be applied in other surgicalapproaches and combinations of surgical approaches to the spinal motionsegment such that one or more stabilization systems 20 are attached tothe anterior, antero-lateral, lateral, and/or postero-lateral portionsof the spinal motion segment.

Stabilization system 20 allows at least small degrees of spinal motionin the spinal motion segment to which it is attached since system 20includes an elongate member 80 that is at least partially flexiblebetween adjacent anchors 30. It should be understood that stabilizationsystem 20 can be used in conjunction with fusion or non-fusion treatmentof the spine. In one form, elongate member 80 is a tether made from oneor polymers, such as, for example, polyester or polyethylene; one ormore superelastic metals or alloys, such as, for example, nitinol; orfrom resorbable synthetic materials, such as, for example suturematerial or polylactic acid. It is further contemplated that elongatemember 80 has elasticity such that when tensioned it will tend to returntoward its pre-tensioned state.

The anchors and coupling members described herein may be employed withstabilization system 20. In addition, it contemplated that the anchorsand coupling members described herein may be employed in isolation or insystems that include two or more coupling members and anchors. Examplesof other systems include: one or more elongate members extendinglaterally across a vertebral body; one or more elongate membersextending in the anterior-posterior directions across a vertebral body;one or more elongate member wrapped around a vertebral body; andcombinations thereof. Further examples include application of theanchors and coupling members of the present invention with bonystructures in regions other than the spinal column.

Referring to FIGS. 2-3, shown therein are various details of an anchor30 according to the present invention. Anchor 30 has a length extendingalong longitudinal axis L1 and includes an elongated shaft 32 and anelongate member receiving portion in the form of a head 34. Shaft 32 caninclude an external thread form 36 in the form of a single thread turnor a plurality of discrete threads. Other engaging structure along shaft32 are also contemplated, such as barbs or pivoting gulls, so long asshaft 32 can engage the bony tissue of the vertebra to which anchor 30is attached. In an alternate form, shaft 32 is in the form of a spinalhook.

In the illustrated embodiment, head 34 has a first arm 34 a spaced froma second arm 34 b. Head 34 defines a U-shaped passage 38 extendingbetween first arm 34 a and second arm 34 b. Head 34 further includes abearing surface 40 extending between first arm 34 a and second arm 34 band along passage 38. Bearing surface 40 further extends from a firstlip 46 a at one end passage 38 to a second lip 46 b at the other end ofpassage 38. Anchor 30 further includes a cannulation 42 extendingthrough shaft 32 along axis L1 and opening at the distal end of shaft32. Cannulation 42 interrupts bearing surface 40 and is in communicationwith passage 38. It is also contemplated that cannulation 42 extendsfrom bearing surface 40 into shaft 32 for only a portion of the lengthof shaft 32.

First arm 34 a has thread form 35 a on an inner side thereof and secondarm 34 b has a thread form 35 b on an inner side thereof. First arm 34 aincludes a first indent 44 a in an outer surface thereof and second arm34 b includes a second indent 44 b in an outer surface thereof. Indents44 a, 44 b are sized to receive fingers from insertion tools,compression instruments, and instruments for inserting and tensioningelongate member 80 or the like to enable their attachment to anchor 30when anchor 30 is engaged to a vertebra.

Referring now to FIGS. 4-7, there will be described coupling member 50.Coupling member 50 has a plug body 52 with an elongate member engagingportion in the form of penetrating element 54 extending distally fromplug body 52. A thread form 56 is formed around plug body 52. Threadform 56 has a thread run-out 56 a on bearing surface 60. Plug body 52further includes a tool receptacle 58 formed therein into which adriving tool is received to apply a rotary driving force to couplingmember 50 to engage coupling member 50 to thread forms 35 a, 35 b ofanchor 30. Coupling member 50 includes a lower bearing surface 60 whichbears against elongate member 80 positioned between anchor 30 andcoupling member 50. Penetrating element 54 includes a distal end 62tapered to facilitate penetration of penetrating element 54 intoelongate member 80.

The anchors and coupling members of the present invention can be formedfrom any suitable biocompatible material. Such material includes metalssuch as, for example, stainless steel or titanium; polymers such as, forexample, polyester and polyethylene; superelastic metals or alloys suchas, for example, nitinol; and resorbable synthetic materials such as,for example, suture material and polylactic acid.

Referring now to FIGS. 8-9, attachment of elongate member 80 to anchor30 with coupling member 50 will be further described. In FIG. 8,elongate member 80 has been positioned through passage 38 and against oradjacent bearing surface 40 of anchor 30. Coupling member 50 is alignedwith the upper opening between first arm 34 a and second arm 34 b.Distal end 62 of penetrating element 54 contacts or partially penetrateselongate member 80. In FIG. 9, coupling member 50 is threadinglyadvanced into head 34 until bearing surface 60 contacts elongate member80 and crimps elongate member 80 between bearing surface 40 and bearingsurface 60, and penetrating element extends completely through elongatemember 80.

Where elongate member 80 is made from compressible material, elongatemember 80 has a reduced cross-sectional area along its crimped portionbetween bearing surfaces 40, 60. Penetrating element 54 is at leastpartially received in cannulation 42 of anchor 30, allowing completepenetration of elongate member 80 by penetrating element 54 incombination with the crimping discussed above. Penetrating element 54provides a bearing member against which elongate member 80 acts as itsis tensioned or compressed with longitudinal forces that would tend tocause elongate member 80 slip in anchor 30. Movement of elongate member80 in anchor 50 is thus resisted by friction generated between elongatemember 80 and bearing surfaces 40, 60 and also by the bearing supportprovided by the penetrating element 54 of coupling member 50.

In FIG. 10, there is illustrated another embodiment anchor 130 accordingto the present invention. Anchor 130 includes an elongated shaft 132 anda head 134. Shaft 132 can include external thread form 136 or other boneengaging structure therealong such as discussed above with respect toanchor 30. In the illustrated embodiment, head 134 as ab elongate memberreceiving portion between a first arm 134 a spaced from a second arm 134b. First arm 134 a has thread form 135 a on an inner side thereof andsecond arm 134 b has a thread form 135 b on an inner side thereof. Head134 defines a U-shaped passage 138 extending between first arm 134 a andsecond arm 134 b. Head 134 further includes a bearing surface 140extending between first arm 134 a and second arm 134 b and along passage138 to a first lip 146 a to a second lip 146 b.

Anchor 130 further includes an elongate member engaging portion in theform of a penetrating element 142 extending from bearing surface 140into passage 138. Elongate member 80 can be placed into passage 138 andpressed against bearing surface 140 such that penetrating element 142extends through elongate member 80. Penetrating element 142 provides abearing member against which elongate member 80 acts to resist tensileor compressive longitudinal forces that would tend to cause elongatemember 80 slip in anchor 130. It is further contemplated in anotherembodiment that anchor 130 is not provided with penetrating element 142.

Referring now to FIGS. 11-13, another embodiment coupling member 150according to the present invention and having application with anchors30, 130 is illustrated. Coupling member 150 has a plug body 152 with athread form 156 therearound. Coupling member 150 includes a distalbearing surface 160 which bears against elongate member 80 whenpositioned between anchor 30, 130 and coupling member 150. Couplingmember 150 also includes an elongate member engaging portion on itsdistal end in the form of a protrusion 154 extending around a toolreceptacle 158. Tool receptacle 158 provides a through-hole by extendingthrough plug body 152. A driving tool is positionable in tool receptacle158 to apply a rotary driving force to coupling member 150 to engagecoupling member 150 to the internally threaded head of anchor 30, 130.

Coupling member 150 presses elongate body 80 between bearing surface 160and the bearing surface in the passage of anchor 30, 130. Protrusion 154crimps elongate member 80 at its contact locations therewith against thebearing surface of the anchor to a reduced size configuration to resistlongitudinal forces exerted on the elongated member. Coupling member 150crimps elongate member 80 at a first location adjacent first lip 46 a,146 a of anchor 30, 130 and at a second location adjacent second lip 46b, 146 b of anchor 30, 130.

For embodiments in which penetrating element 142 is provided on anchor130, penetrating element 142 extends through elongate member 80 and intoreceptacle 158 of coupling member 150 when threadingly engaged to anchor130. Penetrating element 142 provides resistance to longitudinal forcesapplied to elongate member 80 in manner similar to that discussed abovewith respect to penetrating element 54.

Referring now to FIGS. 14-15, a coupling member 250 according to thepresent invention and having application with anchors 30, 130 isillustrated. Coupling member 250 has a plug body 252 with a thread form256 therearound. Coupling member 250 includes a distal bearing surface260 which bears against elongate member 80 positioned between anchor 30,130 and coupling member 250. Coupling member 250 also includes anelongate member engaging portion in the form of a protrusion 254extending around a tool receptacle 258. Tool receptacle 258 extendsthrough plug body 252. A driving tool is positionable in tool receptacle258 to apply a rotary driving force to coupling member 250 to engagecoupling member 250 to the internally threaded head of anchor 30, 130.

Coupling member 250 further includes a break-off portion 262 coupled toplug body 252 at recess 264. Break-off portion 262 has a driving toolreceiving portion 266 formed around tool receptacle 258. In theillustrated embodiment, driving tool receiving portion 266 is configuredto receive a hex-head driving tool; however, other configurations arealso contemplated. A driving tool is positionable in driving toolreceiving portion 266 to drive coupling member 250 into the head ofanchor 30, 130 so that protrusion 254 crimps elongate member 80 at itscontact locations therewith against the bearing surface of the anchor toresist longitudinal forces exerted thereon. It is also contemplatedprotrusion 254 can partially penetrate into elongate member 80 at itscontact locations therewith. Break-off portion 262 severs from plug body252 at recess 264 when a pre-determined amount of torque is appliedthereto. The torque is established such that sufficient compressiveforces are applied to elongate member 80 to prevent it from slippingwith respect to anchor 30, 130, yet the compressive forces are not sogreat so as to sever or otherwise cause elongate member 80 to beineffective as a stabilization element.

For embodiments in which penetrating element 142 is provided on anchor130, penetrating element 142 extends through elongate member 80 and intothe through-hole provided by receptacle 258 of coupling member 250 whenthreadingly engaged to anchor 130. Break-off portion 262 is sizedpositioned with respect to plug body 252 so that the driving tool islocated proximally of tool receptacle 258 and does not interfere withpenetrating element 142 as coupling member 250 is threaded into head 134of anchor 130.

Referring now to FIGS. 16-17, a coupling member 350 according to thepresent invention and having application with anchors 30, 130 isillustrated. Coupling member 350 has a plug body 352 with a thread form356 therearound. Coupling member 350 also includes an elongate memberengaging portion in the form of a cylindrical end member 360 that isattached to a distal end of plug body 352. End member 360 is rotatablerelative to plug body 352 such that as plug body 352 is threaded intothe head of the anchor, end member 360 does not rotate when insufficiently firm contact with elongate member 80. In specificembodiment, plug body 352 includes a lower flange 353 received in anupper cavity 361 of end member 360. A number of pine 365 are press fitor otherwise attached to end member 360 and extend into cavity 361 aboveflange 353 to rotatably capture end member 360 on plug body 352. Otherconfigurations for rotatably engaging end member 360 to plug body 352are also contemplated herein.

End member 360 includes a lower bearing surface 368 which bears againstelongate member 80 when elongate member 80 is positioned between anchor30, 130 and coupling member 350. End member 360 also includes aprotrusion 354 extending around a concave surface 366. Protrusion 354crimps or partially penetrates elongate member 80 at its contact pointstherewith against the anchor bearing surface.

Coupling member 350 includes a tool receptacle (not shown) that at leastextends through plug body 352. The tool receptacle may extend throughend member 360 to receive a penetrating element extending from theanchor. It is further contemplated that concave surface 366 can be solidand contact the anchor penetrating element when coupling member 350 isengaged thereto, or that the penetrating element only partiallypenetrates the elongate member. Coupling member 350 can also include abreak-off portion 362 and recess 364 such as described above withrespect to coupling member 250.

Referring now to FIG. 18, a coupling member 450 according to the presentinvention and having application with anchors 30, 130 is illustrated.Coupling member 450 has a plug body 452 having a thread form 456therearound. Coupling member 450 also includes an elongate memberengaging portion in the form of cylindrical end member 460 that isattached to plug body 452 and rotatable with respect thereto. Couplingmember 450 includes a tool receptacle (not shown) that extends throughplug body 452 but not through end member 460. Coupling member 450 canalso include a break-off portion 462 such as described above withrespect to coupling member 250. End member 460 includes a lower bearingsurface 466 having protrusions 454 which partially penetrate or crimpelongate member 80 against the anchor bearing surface at a number oflocations between first lip 46 a, 146 a and second lip 46 b, 146 b. Inthe illustrated embodiment, these irregularities are formed by a grid ofa plurality of pyramid shaped protrusions.

An alternate form of coupling member 450 is shown in FIG. 19 anddesignated at 550. Coupling member 550 is generally identical tocoupling member 450 and includes a plug body 552 having a thread form556 therearound, a break-off portion 562, and a cylindrical end member560 having a lower bearing surface 566 with protrusions 554 that aresimilar to protrusions 454. Coupling member 550 further includes passage558 extending therethrough and opening at lower bearing surface 566.While coupling member 550 may be used with any embodiment anchordiscussed herein, coupling member 550 is particularly useful if anchor130 is provided with a penetrating element 142 since penetrating element142 can completely penetrate the elongate member and be received inpassage 558.

Referring now to FIGS. 20-21, another embodiment coupling member 750 isillustrated. Coupling member 750 has a plug body 752 having a threadform 756 therearound. Coupling member 750 includes a tool receptacle(not shown) that extends at least through plug body 752. Coupling member750 can also include a break-off portion 762 such as described abovewith respect to coupling member 250. Coupling member 750 includeselongate member engaging portion having an end member 760 on rotatablyengage to plug body 752.

End member 760 is an elongated body having a first longitudinalextension 760 a and a second longitudinal extension 760 b extending froma center portion 760 c. Center portion 760 c is sized and shaped to bereceived in the passage of the anchor adjacent the anchor bearingsurface. Longitudinal extensions 760 a, 760 b are sized to be receivedin passage 38, 138 of anchor 30, 130 and extending longitudinally in thedirection of elongate member 80 between the anchor arms and beyond theadjacent one of the first lip 46 a, 146 a and second lip 46 b, 146 b. Alower bearing surface 766 is formed along end member 760 between a firstprotrusion 754 a and a second protrusion 754 b. Protrusions 754 a, 754 bcontact elongate member 80 and crimp it between lip 46 a, 146 a or 46 b,146 b and the adjacent protrusion 754 a, 754 b. Lower bearing surface766 contacts elongate member 80 in the passage of the anchor such that africtional bearing relationship is established between lower bearingsurface 766 and the entire length of the bearing surface of the anchorbetween lips 46 a, 46 b or 146 a, 146 b.

An alternate form of coupling member 750 is shown in FIG. 22 anddesignated at 850. Coupling member 850 is generally identical tocoupling member 750 and includes a plug body 852 having a thread form856 therearound, a break-off portion 862 and recess 864, and an endmember 860 having a first longitudinal extension 860 a, a secondlongitudinal extension 860 b, a central portion 860 c, and a lowerbearing surface 866 extending therealong. The engagement of elongatemember 80 between anchor 30, 130 and coupling member 850 relies entirelyon the frictional engagement provided by the contact surface area oflower bearing surface 866 and the bearing surface of the anchor betweenfirst lip 46 a, 146 and second lip 46 b, 146 b. Utilizing the entirelength of the anchor bearing surface to crimp elongate member 80provides greater resistance to slippage of elongate member 80 betweencoupling member 50 and anchor 30 than would be provided if only aportion of the bearing surface of the anchor were utilized.

Another form of coupling member 750 is shown in FIG. 23 and designatedat 950. Coupling member 950 is generally identical to coupling member750 and includes a plug body 952 having a thread form 956 therearound, abreak-off portion 962 and recess 964, and an end member 960 having afirst longitudinal extension 960 a, a second longitudinal extension 960b, and a central portion 960 c therebetween with a lower bearing surface966 extending therealong. Coupling member 950 also includes longitudinalmember engaging portions in the form of a first penetrating element 954a and second penetrating element 954 b having tapered ends 955 a and 955b, respectively. As shown further in FIG. 23 a, penetrating elements 954a, 954 b extend downwardly from bearing surface 966 a sufficientdistance in order to partially or completely penetrate elongate member80 positioned between anchor 30, 130 and coupling member 950.Longitudinal extensions 960 a, 960 b are sized to extend longitudinallyalong elongate member 80 beyond the passage of the anchor 30, 130 towhich it is attached so that penetrating elements 954 a, 954 b penetrateelongate member 80 outside passage 38, 138.

Referring now to FIGS. 24-25, another embodiment coupling member 1050 isillustrated. Coupling member 1050 has a plug body 1052 having a threadform 1056 therearound. Coupling member 1050 includes a tool receptacle(not shown) that extends at least through plug body 1052. Couplingmember 1050 can also include a break-off portion 1062 such as describedabove with respect to coupling member 250. Coupling member 1050 alsoincludes end member 1060 in the form of an elongate body that isattached to plug body 1052 and rotatable with respect thereto.

End member 1060 includes a first longitudinal extension 1060 a, a secondlongitudinal extension 1060 b, and central portion 1060 c therebetween.A spring loaded arm 170 is pivotally coupled at one end to secondlongitudinal extension 1060 b. A spring 180 biases the opposite end ofarm 1070 away from end member 1060. Arm 1070 can also include a roundedportion 1072 having protrusions in the form of a plurality of teeth 1074formed thereacross along a lower side thereof. Elongate member 80 can bepulled or tensioned in the direction of arrow T since spring 1080compresses to allow such tensioning. If elongate member 80 moves in thedirection opposite arrow T, arm 170 provisionally captures elongatemember 80 in its tensioned state with teeth 1074 spring biased againstthe tensioned elongate member 80. Teeth 1074 on arm 1070 frictionallyengage or partially penetrate the tensioned elongate member 80 toprevent it from slipping until coupling member 1050 is secured to theanchor with spring 1080 compressed.

It is contemplated that the penetrating elements and protrusions of thepresent invention can extend completely through elongate member 80, orextend partially through elongate member 80. In one specific embodiment,it is contemplated that the partial penetration depth into elongatemember 80 corresponds to about 5 percent of its thickness. Otherpenetration depths ranging from 5 percent to 100 percent are alsocontemplated. It is further contemplated that elongate member 80 can beprovided with a substantially solid body and the penetrating elementsand protrusions of the present invention pierce this solid body ascoupling member is threadingly advanced into head 34.

In view of the systems and devices discussed above, a method forstabilizing a spinal motion segment will be described. An elongatemember is provided with a length sufficient to extend along the spinalmotion segment to which it is to be attached. Anchors are engaged torespective ones of the vertebrae comprising the spinal motion segment.Adjacent anchor can be compressed toward one another, and the elongatemember attached to each of the compressed anchors to provide correctiveforces to the spinal motion segment. It is contemplated that theelongate member can be crimped or penetrated as discussed above toprevent slippage of the elongate member with respect to the anchors towhich it is attached. Since elongate member 80 can be penetrated orcrimped at any location along its length with the anchors and couplingmembers of the present invention, elongate member 80 can be providedwith a solid, uniform body along its length. Elongate member 80 need notinclude any holes, slots or other engaging features along its length forengagement to the anchors and coupling members of the present invention.Thus, the surgeon is not constrained to particular, discrete attachmentlocations along elongate member 80, but rather is provided an infinitenumber of attachment locations along elongate member 80.

According to a further method for stabilizing a spinal motion segment,an elongate member is provided with a length extending between at leasttwo vertebrae of the spinal motion segment. Anchors are engaged tovertebrae of the spinal motion segment. The elongate member is tensionedto provide the desired corrective force to the spinal motion segment andthen attached to the anchors with coupling members. It is contemplatedthat the elongate member can be crimped or penetrated as discussed aboveto prevent slippage of the elongate member with respect to the anchorsto which it is attached. It is further contemplated that the first andsecond anchors can be compressed toward one another before the tensionedelongate member is attached to the first and second anchors. Theelongate member can then be cut by the surgeon to remove any excesslength.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinvention are desired to be protected.

1-55. (canceled)
 56. A method for stabilizing a spinal motion segment,comprising: providing an elongate member having a length extendingbetween at least two vertebrae and being at least partially formed of aflexible material; engaging a first anchor and a second anchor torespective ones of a first vertebra and a second vertebra; tensioningthe elongate member; and penetrating the tensioned elongate member toattach the tensioned elongate member to the first and second anchors.57. (canceled)
 58. The method of claim 56, further comprising: engaginga third anchor to a third vertebral body adjacent the second vertebralbody; tensioning the elongate member between second anchor and the thirdanchor; and attaching the elongate member to the third anchor.
 59. Themethod of claim 56, further comprising completely penetrating theelongate member to attach it to the first and second anchors.
 60. Themethod of claim 56, wherein penetrating the elongate member includespiercing a solid body portion of the elongate member.
 61. A method forstabilizing a spinal motion segment, comprising: providing an elongatemember having a length extending between at least two vertebrae andbeing at least partially formed of a flexible material; engaging a firstanchor and a second anchor to respective ones of a first vertebra and asecond vertebra; penetrating the elongate member to attach the elongatemember to the first and second anchors. 62-63. (canceled)
 64. The methodof claim 61, further comprising: engaging a third anchor to a thirdvertebral body adjacent the second vertebral body; tensioning theelongate member between second anchor and the third anchor; andattaching the elongate member to the third anchor.
 65. The method ofclaim 61, wherein penetrating the elongate member includes piercing theelongate member to attach it to the first and second anchors.
 66. Themethod of claim 65, wherein the elongate member has a substantiallysolid body and piercing the elongate member includes piercing the solidbody. 67-95. (canceled)
 96. The method of claim 56, wherein saidelongate member has an outer surface and an interior, and saidpenetrating includes extending a penetrating member through said outersurface so that the penetrating member is at least partially within saidinterior of said elongate member.
 97. The method of claim 58, whereinattaching the elongate member to the third anchor includes penetratingthe elongate member.
 98. The method of claim 97, wherein penetrating theelongate member includes piercing the elongate member.
 99. The method ofclaim 64, wherein attaching the elongate member to the third anchorincludes penetrating the elongate member.
 100. The method of claim 99,wherein penetrating the elongate member includes piercing the elongatemember.
 101. The method of claim 61, wherein: the first and secondanchors each include an upper U-shaped channel configured for receipt ofa portion of the elongate member; the first and second anchors eachinclude a plug with a threaded upper portion and a piercing lowerportion, the plug being movable in the channel by engagement of thethreaded upper portion to an inner threaded surface of each of the firstand second anchors; and penetrating the elongate member is performed bythe piercing lower portion of the plug.
 102. The method of claim 61,wherein said elongate member has an outer surface and an interior, andsaid penetrating includes extending a penetrating member through saidouter surface so that the penetrating member is at least partiallywithin said interior of said elongate member.
 103. The method of claim61, wherein said elongated member has elasticity such that whentensioned said elongated member tends to return toward a pre-tensionedstate.
 104. A method for stabilizing a spinal motion segment,comprising: engaging a first anchor and a second anchor to respectiveones of a first vertebra and a second vertebra; positioning an elongatemember within U-shaped channels disposed in the first and secondanchors, the elongate member having a length extending between at leastthe first and second vertebrae and being at least partially formed of aflexible material; tensioning the elongate member; and piercing theelongate member with plugs to attach the elongate member to the firstand second anchors, the plugs being moveable in the U-shaped channels.105. The method of claim 104, further comprising compressing the firstand second anchors engaged to the first and second vertebrae toward oneanother.
 106. The method of claim 104, wherein said elongate member hasan outer surface and an interior, and said penetrating includesextending a penetrating member through said outer surface so that thepenetrating member is at least partially within said interior of saidelongate member.
 107. The method of claim 104, wherein said elongatedmember has elasticity such that when tensioned said elongated membertends to return toward a pre-tensioned state.